Method of chilling foodstuffs and the like



June 30, 1964 W. L. MORRISON METHOD OF CHILLING FOODSTUFFS AND THE LIKE Filed May 25, 1960 12 i I l 2 INVENTOR.

(Lg [lard L.fl(0rris0m Parker & CarTer United States Patent 3,138,935 METHOD OF CI-HLLINIGKIEOODSTUFFS AND THE Willard L. Morrison, Lake Forest, Ill., assignor to Liquefreeze Company, Inc., New York, N.Y., a corporation of New York Filed May 25, 1960, Ser. No. 31,781- 6 Claims. (CI. 62-64) My invention relates to improvements in method of chilling foodstuffs and the like and has for one object to provide a new and improved means whereby foodstuffs may be chilled for shipment and storage to temperatures far below those characteristic of the usual frozen food industry.

I propose preferably to chill the food in two stages. In the first stage, packages or relatively small cartons enclosing a plurality of packages will be cooled to a point below the freezing point so that the contents of the package becomes solid, hard and is able to support substantial loads independent of and without regard to the strength of the wrapper, carton or box containing the package. These packages will be packed in an insulating storage and shipper container with sufiicient space between the packages to permit flow or penetration of gas and liquid therebetween. Thereafter an inert, cold boiling liquid, for example, nitrogen liquid at atmospheric pressure at 320 degrees F. will be poured into the container and because the temperature of the food packages therein is far above the boiling temperature of the liquid, heat will be extracted from the foodstuffs to boil the liquid and change it from a liquid to a gas with consequent great expansion of volume.

The gas which boils off from the liquid will, because of the expansion resulting from the change from liquid to gaseous state, circulate through the insulated container penetrating between the food packages, thus cooling by heat exchange those packages which do not come in contact with the liquid and are not cooled directly as they furnish the heat to boil the liquid.

The liquid may be poured on the upper layers in the container, will boil ofi and as the upper layers are cooled the liquid will penetrate further and further down into the mass before it is evaporated until the entire mass has been chilled.

The liquid may on the other hand be introduced at the bottom of the mass, boiling takes place as before and the evolved cold gas is by expansion forced upwardly along, around and about the packages to escape at the top of the container, cooling by heat exchange with the gas those packages that were not contacted by the liquid.

If desired, this freezing may take the form of a single stage operation. In that case, however, it becomes necessary that the wrappers of the individual packages, cartons or boxes stacked in the container have strength independent of their contents to cause the packages in the lower levels to support the weight of the packages above them until the foodstuffs are frozen, because if unfrozen foodstuffs were packed in the shipper container in the conventional form of packages of paper or cardboard or the like, the weight of the packages above would cause such crushing, distortion and spreading of the lower packages as to spoil their marketable value and also cause such flowing of the material that gas or liquid penetration about the packages would be prevented.

My invention is illustrated more or less diagrammatically in the accompanying drawing, wherein:

FIGURE 1 is a section through a suitable storage and shipper container;

FIGURE 2 is a similar section illustrating a modified form.

3,138,935 Patented June 30., 1964 Like parts are indicated by like characters throughout the specification and drawings.

The shipper container has an outer Wall 1, an inner wall 2. Insulation 3 between the two walls holds them in proper relative position though other means might be provided to hold them in shape. The container is open at the top and has an insulated removable cover 4. 5 rep resents packages of foodstuifs within the container, substantially filling it but so packed that there is space between and about the packages for liquid and gas flow.

6 is a source of cold boiling liquid, for example1iquid nitrogen at atmospheric pressure at a temperature of -320 degrees F. '7 is a duct leading from the source for discharge of the liquid on the upper portion of the contents of the container. 8 are means for holding the lid of the container in open position for escape of the gas in vaporous condition after it has boiled off.

In FIGURE 2, the situation is the same except that the cover 9 has a port 10 through which gas may be fed through a supply pipe 11 which extends to the bottom of the container. The supply pipe receives liquid gas as before from a suitable source. The port is of such size that the gas boiled off from the liquid may escape without generating undue pressure in the container and after the desired temperature has been reached, may be closed by a removable lid 12.

The container will be packed preferably with the frozen food bodies at temperatures far above that ultimately desired but below freezing and the space between them as well as any clearance or space between the foodstuffs and the containers will be filled with air. As the neutral gas boils off from the liquid and expands, it will tend to expel the air from the container and will in any event entrain as it passes out much of the air so that in the end when the supply of gas has been sufficient to lower the temperature to the desired point, there will be little if any air left in the container and the foodstuffs will be exposed to a neutral inert atmosphere which inhibits much of the bacterial or vegetable growth which sometimes causes food deterioration. Thus, in connection with the preservation of foods stored and shipped in my container, both the neutral atmosphere and the air contribute.

By the term inert used in the specification and claims as describing the gas used as a coolant either in a liquid or gaseous form, I mean a gas which contains little if any oxygen and has no other elements which would unite with or upon penetration into the foodstuffs cause deterioration, change in taste, or of any toxic result and the gases nitrogen, helium, and argonfall into the category of inert gases in the sense intended.

This application is a continuation-in-part of my copending application Serial No. 530,347, now abandoned, filed August 24, 1955, which is a continuation-in-part of application Serial No. 514,321, issued as Patent No. 2,831,329 issued April 22, 1958.

As the liquid nitrogen at atmospheric pressure is poured into the container, it penetrates the interstitial spaces therein, wets the walls of the latter and is boiled and evaporated by the heat of the container contents. This boiling and evaporation continues after the supply of liquid nitrogen has ceased until all the liquid has boiled away.

As the liquid boils, it expands some six hundred times and drives out most, if not all of the air in the container. When the method above outlined is carried out there results at closed insulated container containing a body of frozen perishable material Wet with liquid nitrogen and surrounded by an inert, cold atmosphere largely of nitrogen at substantially atmospheric pressure.

I have illustrated the container very diagrammatically as a box. The shape of the box, its size and the way in which it may be handled when loaded forms no part of the present invention. The invention involves the relationship between the container, the contents, the nitrogen and the atmosphere in the container and the hold of a ship or the body of a truck or freight cars just as much a container as is the square box diagrammatically shown in the drawing.

I claim:

1. A method of chilling foodstuffs and other perishable materials in a container for extended periods of time including the steps of exposing the materials to be chilled in a container to heat exchange relationship with liquid nitrogen at substantially atmospheric pressure, extracting heat from the materials being chilled to thereby lower the temperature of at least the outer portions of the materials to a point substantially below zero degrees F., ceasing the supply of liquid nitrogen before the liquid nitrogen has completely vaporized, and maintaining a condition of substantial equilibrium of pressure within and without the container by permitting escape of additional vapor generated by extraction of heat from the materials by the liquid nitrogen subsequent to cease of supply of liquid nitrogen.

2. A method of preserving foodstutfs and other perishable materials in a container for extended periods of time, including the steps of exposing the materials to be preserved in a container to liquid nitrogen in a heat exchange relationship at a temperature substantially below zero degrees F. and at a pressure substantially equal to atmospheric pressure, reducing the temperature of the materials being preserved to a point substantially equal to the temperature of the liquid nitrogen by vaporizing the liquid nitrogen, expelling air and other gases from the container, ceasing the supply of liquid nitrogen before the liquid nitrogen has completely vaporized and before the air and other gases in the container have been substantially completely expelled, and maintaining substantially atmospheric pressure in the container by bleeding off nitrogen gas generated by heat absorption by the liquid nitrogen from the materials being preserved.

3. A method of superchilling foodstuffs and other perishable materials in a container for extended periods of time including the steps of exposing materials packed in a container with clearance spaces therearound for liquid nitrogen in direct heat exchange relationship at substantially atmospheric pressure, extracting heat from the materials being chilled as the liquid nitrogen flows into the clearance spaces to thereby superchill at least the outer portions of the materials to a temperature substantially equal to the temperature of the liquid nitrogen, ceasing the supply of liquid nitrogen before the liquid nitrogen has completely vaporized, to thereby provide a reservoir of refrigerant, and maintaining during the continuing refrigerating action occurring after the cease of supply of liquid nitrogen, a condition of substantial equilibrium of pressure within and Without the container by bleeding off excess vapor generated by heat absorption from the materials being chilled.

4. A method of chilling and preserving foodstufis and other perishable materials for extended periods of time including the steps of lowering the temperature of the materials to be preserved to atemperature in the range of 32 degrees F. to slightly therebelow, inducing a heat exchange relationship at substantially atmospheric pressure between the materials being preserved and liquid nitrogen in a container, extracting heat from the materials being preserved to thereby lower the temperature of at least the outer portions of the materials to a point substantially equal to the temperature of the liquid nitrogen, ceasing the supply of liquid nitrogen before the liquid nitrogen has completely vaporized, and maintaining a condition of substantial equilibrium of pressure within and without the container by permitting escape of additional vapor generated by heat absorption by the liquid nitrogen from the materials being preserved subsequent to the cease of supply of liquid nitrogen.

5. A method of chilling and preserving foodstufis and other perishable materials for extended periods of time including the steps of preliminarily freezing the materials to be preserved to a temperature in the range of 32 degrees F. to slightly therebelow, placing the frozen materials in a container at substantially atmospheric pressure, exposing the frozen materials to liquid nitrogen, extracting heat from the frozen materials to thereby lower lower the temperature of at least the outer portions of the materials to a point substantially equal to the temperature of the liquid nitrogen, ceasing the supply of liquid nitrogen before the liquid nitrogen has completely vaporized, and maintaining a condition of substantial equilibrium of pressure within and without the container by permitting escape of vapor generated by heat absorption by the liquid nitrogen from the materials after ceasing the supply of liquid nitrogen.

6. A method of chilling and preserving foodstuffs and other perishable materials for extended periods of time including the steps of lowering the temperature of the materials to be preserved to a temperature in the range of 32 degrees F. to slightly therebelow whereby the materials become substantially self-sustaining, placing the self-sustaining materials in a container, introducing liquid nitrogen at substantially atmospheric pressure into the container and into heat exchange relationship with the materials therein, extracting heat from the materials being chilled to thereby lower the temperature of at least the outer portions of the material to a point substantially equal to the temperature of the liquid nitrogen, ceasing the supply of liquid nitrogen, and maintaining a condition of substantial equilibrium of pressure within and without the container by permitting escape of vapor generated by heat absorption by the liquid nitrogen from the materials after ceasing the supply of liquid nitrogen.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A METHOD OF CHILLING FOODSTUFFS AND OTHER PERISHABLE MATERIALS IN A CONTAINER FOR EXTENDED PERIODS OF TIME INCLUDING THE STEPS OF EXPOSING THE MATERIALS TO BE CHILLED IN A CONTAINER TO HEAT EXCHANGE RELATIONSHIP WITH LIQUID NITROGEN AT SUBSTANTIALLY ATMOSPHERIC PRESSURE, EXTRACTING HEAT FROM THE MATERIALS BEING CHILLED TO THEREBY LOWER THE TEMPERATURE OF AT LEAST THE OUTER PORTIONS OF THE MATERIALS TO A POINT SUBSTANTIALLY BELOW ZERO DEGREES F., CEASING THE SUPPLY OF LIQUID NITROGEN BEFORE THE LIQUID NITROGEN HAS COMPLETELY VAPORIZED, AND MAINTAINING A CONDITION OF SUBSTANTIAL EQUILIBRIUM OF PRESSURE WITHIN AND WITHOUT THE CONTAINER BY PERMITTING ESCAPE OF ADDITIONAL VAPOR GENERATED BY EXTRACTION OF HEAT FROM THE MATERIALS BY THE LIQUID NITROGEN SUBSEQUENT TO CEASE OF SUPPLY OF LIQUID NITROGEN. 